/// <summary>
/// 获取水印区域
/// </summary>
/// <param name="inputImage">待加水印的图像</param>
/// <param name="watermarkImage">用为水印的图像</param>
/// <returns>返回水印矩形区域</returns>
private Rectangle GetWatermarkArea(Image inputImage, Image watermarkImage)
{
Rectangle imageArea = new Rectangle(Point.Empty, inputImage.Size);
Rectangle watermarkArea = new Rectangle(Point.Empty, watermarkImage.Size);
RectangleUtil.PositionRectangle(this.AnchorLocation, imageArea, ref watermarkArea);
//为边缘留出偏移量
int offsetX = (int)((float)inputImage.Width * (float).01);
int offsetY = (int)((float)inputImage.Height * (float).01);
switch (AnchorLocation)
{
case AnchorLocation.LeftTop:
watermarkArea.Offset(offsetX, offsetY);
break;
case AnchorLocation.MiddleTop:
watermarkArea.Offset(0, offsetY);
break;
case AnchorLocation.RightTop:
watermarkArea.Offset(-offsetX, offsetY);
break;
case AnchorLocation.LeftMiddle:
watermarkArea.Offset(offsetX, 0);
break;
case AnchorLocation.Middle:
break;
case AnchorLocation.RightMiddle:
watermarkArea.Offset(-offsetX, 0);
break;
case AnchorLocation.LeftBottom:
watermarkArea.Offset(offsetX, -offsetY);
break;
case AnchorLocation.MiddleBottom:
watermarkArea.Offset(0, -offsetY);
break;
case AnchorLocation.RightBottom:
watermarkArea.Offset(-offsetX, -offsetY);
break;
}
return(watermarkArea);
}
/// <summary>
/// 按照期望的宽高比获取sourceRect中最大矩形区域
/// </summary>
/// <param name="sourceRect">源矩形区域</param>
/// <param name="desiredAspect">期望的宽高比</param>
/// <param name="anchorLocation">矩形选区停靠位置</param>
/// <returns>返回在sourceRect内满足desiredAspect的最大矩形区域</returns>
protected virtual Rectangle GetLargestInset(Rectangle sourceRect, float desiredAspect, AnchorLocation anchorLocation)
{
Rectangle destRect = default(Rectangle);
float sourceAspect = (float)sourceRect.Width / (float)sourceRect.Height;
float ratioScale = desiredAspect / sourceAspect;
if (sourceAspect > desiredAspect)
{
destRect.Width = (int)((float)sourceRect.Width * ratioScale);
destRect.Height = sourceRect.Height;
}
else
{
destRect.Width = sourceRect.Width;
destRect.Height = (int)((float)sourceRect.Height / ratioScale);
}
RectangleUtil.PositionRectangle(anchorLocation, sourceRect, ref destRect);
return(destRect);
}
/// <summary>
/// 获取水印区域
/// </summary>
/// <param name="graphics">画布</param>
/// <param name="inputImage">图像</param>
/// <param name="watermarkFont">水印文字使用的字体</param>
/// <returns>返回水印矩形区域</returns>
protected virtual Rectangle GetWatermarkArea(Graphics graphics, Image inputImage, out Font watermarkFont)
{
//根据图片的大小我们来确定添加上去的文字的大小
int[] sizes = new int[] { 16, 14, 12, 10, 8, 6, 4, 3, 2, 1 };
//字体
watermarkFont = null;
Size watermarkSize = Size.Empty;
//利用一个循环语句来选择我们要添加文字的型号
//直到它的长度比图片的宽度小
for (int i = 0; i < sizes.Length; i++)
{
watermarkFont = new Font("arial", sizes[i], FontStyle.Bold);
//测量用指定的 Font 对象绘制并用指定的 StringFormat 对象格式化的指定字符串。
watermarkSize = graphics.MeasureString(Text, watermarkFont).ToSize();
if (watermarkSize.Width < (inputImage.Width * 0.8))
{
break;
}
}
Rectangle imageArea = new Rectangle(Point.Empty, inputImage.Size);
Rectangle watermarkArea = new Rectangle(Point.Empty, watermarkSize);
RectangleUtil.PositionRectangle(this.AnchorLocation, imageArea, ref watermarkArea);
//为边缘留出偏移量
int offsetX = (int)((float)inputImage.Width * (float).01);
int offsetY = (int)((float)inputImage.Height * (float).01);
switch (AnchorLocation)
{
case AnchorLocation.LeftTop:
watermarkArea.Offset(offsetX, offsetY);
break;
case AnchorLocation.MiddleTop:
watermarkArea.Offset(0, offsetY);
break;
case AnchorLocation.RightTop:
watermarkArea.Offset(-offsetX, offsetY);
break;
case AnchorLocation.LeftMiddle:
watermarkArea.Offset(offsetX, 0);
break;
case AnchorLocation.Middle:
break;
case AnchorLocation.RightMiddle:
watermarkArea.Offset(-offsetX, 0);
break;
case AnchorLocation.LeftBottom:
watermarkArea.Offset(offsetX, -offsetY);
break;
case AnchorLocation.MiddleBottom:
watermarkArea.Offset(0, -offsetY);
break;
case AnchorLocation.RightBottom:
watermarkArea.Offset(-offsetX, -offsetY);
break;
}
return(watermarkArea);
}
